--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/freeglut/progs/demos/Fractals_random/fractals_random.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,393 @@
+/* fractals_random.c */
+/* This demo shows a single-buffering "freeglut" example. */
+
+/*
+ * Program to draw a fractal by Michael Barnsley's stochastic algorithm.
+ * Algorithm:
+ *  (1) Define the affine transformations (of the form r(i+1) = A r(i) + b )
+ *  (2) Find the stationary point for the first transformation
+ *  (3) To draw:
+ *        - Pick a random integer between 1 and the number of transformations (inclusive)
+ *        - Send the current point through the transformation to create the new current point
+ *        - Plot the new current point
+ */
+
+/*
+ * User Commands:
+ *  PgUp, PgDn - increase/decrease scaling
+ *  Arrow keys - translate viewing section
+ *  r - reset view
+ *  Escape - quit
+ */
+
+#include <GL/freeglut.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#define FGH_PI       3.14159265358979323846
+#ifdef _MSC_VER
+/* DUMP MEMORY LEAKS */
+#include <crtdbg.h>
+#endif
+
+typedef struct
+{
+  double a00, a01, a10, a11 ;   /* Transformation matrix */
+  double b0, b1 ;               /* Constant vector added on */
+  double statx, staty ;         /* Coordinates of the stationary point */
+}
+AffineTrans ;
+
+/* Number of levels to draw the fractal */
+static int num_levels = 0 ;
+
+/* The definition of the fractal */
+static int num_trans ;
+static AffineTrans *affine ;
+
+/* the window title */
+char window_title [ 80 ] ;
+
+/* The amount the view is translated */
+double xwin = 0.0, ywin = 0.0 ;
+double scale_factor = 1.0 ;
+
+/* The current point */
+double current_x = 0.0, current_y = 0.0 ;
+
+/* Signals when a glClear is needed */
+static GLboolean needClear = GL_TRUE;
+
+static void draw_level ( int num, double m00, double m01, double m10, double m11, double n0, double n1 )
+{
+  /* Draw a fractal transformed by "M", "N" as passed in */
+  int i ;
+
+  for ( i = 0; i < 10; i++ )
+  {
+    int random = ( rand( ) >> 10 ) % num_trans;
+    double new_x = affine[random].a00 * current_x + affine[random].a01 * current_y + affine[random].b0 ;
+    double new_y = affine[random].a10 * current_x + affine[random].a11 * current_y + affine[random].b1 ;
+    
+    glVertex2d ( new_x, new_y ) ;
+    current_x = new_x ;
+    current_y = new_y ;
+  }
+}
+
+static void 
+Display(void)
+{
+  if (needClear) {
+    glClear(GL_COLOR_BUFFER_BIT);
+    needClear = GL_FALSE;
+  }
+
+  /* the curve */
+  glPushMatrix();
+  glScaled(2.5, 2.5, 2.5);
+
+  glColor4f(0.0, 0.0, 0.0, 1.0);
+  glBegin ( GL_POINTS ) ;
+  draw_level ( num_levels, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0 );
+  glEnd () ;
+
+  glPopMatrix();
+
+  glFlush();
+  glutPostRedisplay();  /* Needed so that this function will be called again */
+}
+
+static void 
+Reshape(int width, int height)
+{
+  float ar;
+  glViewport(0, 0, width, height);
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity();
+  ar = (float) width / (float) height;
+  if( ar > 1 )
+      glFrustum(-ar, ar, -1.0, 1.0, 2.0, 100.0);
+  else
+      glFrustum(-1.0, 1.0, -1/ar, 1/ar, 2.0, 100.0);
+  glMatrixMode(GL_MODELVIEW);
+  glLoadIdentity();
+  xwin = -1.0 ;
+  ywin =  0.0 ;
+  glTranslated(xwin, ywin, -5.0);
+  needClear = GL_TRUE;
+}
+
+static void 
+Key(unsigned char key, int x, int y)
+{
+  int changed_settings = 1;
+  
+  switch (key) {
+  case 27:  /* Escape key */
+    glutLeaveMainLoop ();
+    break;
+
+  case 'r' :  case 'R' :
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+    xwin = -1.0 ;
+    ywin = 0.0 ;
+    glTranslated(xwin, ywin, -5.0);
+    break ;
+
+  default:
+    changed_settings = 0;
+    break;
+  }
+  if (changed_settings)
+    needClear = GL_TRUE;
+  glutPostRedisplay();
+}
+
+static void 
+Special(int key, int x, int y)
+{
+  int changed_settings = 1;
+
+  switch (key) {
+  case GLUT_KEY_UP :
+    glMatrixMode(GL_MODELVIEW);
+    ywin += 0.1 * scale_factor ;
+    glTranslated(0.0, 0.1 * scale_factor, 0.0);
+    break ;
+
+  case GLUT_KEY_DOWN :
+    glMatrixMode(GL_MODELVIEW);
+    ywin -= 0.1 * scale_factor ;
+    glTranslated(0.0, -0.1 * scale_factor, 0.0);
+    break ;
+
+  case GLUT_KEY_LEFT :
+    glMatrixMode(GL_MODELVIEW);
+    xwin -= 0.1 * scale_factor ;
+    glTranslated(-0.1 * scale_factor, 0.0, 0.0);
+    break ;
+
+  case GLUT_KEY_RIGHT :
+    glMatrixMode(GL_MODELVIEW);
+    xwin += 0.1 * scale_factor ;
+    glTranslated(0.1 * scale_factor, 0.0, 0.0);
+    break ;
+
+  case GLUT_KEY_PAGE_UP :
+    glMatrixMode(GL_MODELVIEW);
+    glTranslated ( -xwin, -ywin, 0.0 ) ;
+    glScaled(1.25, 1.25, 1.25);
+    glTranslated ( xwin, ywin, 0.0 ) ;
+    scale_factor *= 0.8 ;
+    break ;
+
+  case GLUT_KEY_PAGE_DOWN :
+    glMatrixMode(GL_MODELVIEW);
+    glTranslated ( -xwin, -ywin, 0.0 ) ;
+    glScaled(0.8, 0.8, 0.8);
+    glTranslated ( xwin, ywin, 0.0 ) ;
+    scale_factor *= 1.25 ;
+    break ;
+
+  default:
+    changed_settings = 0;
+    break;
+  }
+  if (changed_settings)
+    needClear = GL_TRUE;
+
+  glutPostRedisplay();
+}
+
+
+static int mouse_x = 0, mouse_y = 0 ;
+static int button_down = GLUT_DOWN ;
+
+static void 
+Mouse ( int button, int updown, int x, int y )
+{
+  button_down = updown ;
+
+  if ( updown == GLUT_DOWN )
+  {
+    mouse_x = x ;
+    mouse_y = y ;
+  }
+}
+
+static void 
+MouseMotion ( int x, int y )
+{
+  int window_width  = glutGet ( GLUT_WINDOW_WIDTH  ) ;
+  int window_height = glutGet ( GLUT_WINDOW_HEIGHT ) ;
+  int window_size = ( window_width < window_height ) ? window_width : window_height ;
+
+  double delta_x = 5.0 * (double)(x - mouse_x) / (double)(window_size) ;
+  double delta_y = 5.0 * (double)(y - mouse_y) / (double)(window_size) ;
+
+  xwin += delta_x * scale_factor ;
+  ywin -= delta_y * scale_factor ;
+  glMatrixMode ( GL_MODELVIEW ) ;
+  glTranslated ( delta_x * scale_factor, -delta_y * scale_factor, 0.0 ) ;
+
+  needClear = GL_TRUE;
+  glutPostRedisplay();
+
+  mouse_x = x ;
+  mouse_y = y ;
+}
+
+static void 
+MouseWheel ( int wheel_number, int direction, int x, int y )
+{
+  double scale = ( direction > 0 ) ? 1.25 : 0.8 ;
+
+  glMatrixMode ( GL_MODELVIEW ) ;
+  glTranslated ( -xwin, -ywin, 0.0 ) ;
+  glScaled ( scale, scale, scale ) ;
+  glTranslated ( xwin, ywin, 0.0 ) ;
+  scale_factor /= scale ;
+
+  needClear = GL_TRUE;
+  glutPostRedisplay();
+}
+
+
+static void
+checkedFGets ( char *s, int size, FILE *stream )
+{
+  if ( fgets ( s, size, stream ) == NULL ) {
+    fprintf ( stderr, "fgets failed\n");
+    exit ( EXIT_FAILURE );
+  }
+}
+
+
+void readConfigFile ( char *fnme )
+{
+  FILE *fptr = fopen ( fnme, "rt" ) ;
+  int i ;
+  char inputline [ 256 ] ;
+
+  if ( fptr )
+  {
+    /* Read a header line */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+
+    /* Read a comment line */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+
+    /* Read the window title */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+    /* We assume here that this line will not exceed 79 characters plus a 
+       newline (window_title is 80 characters long). That'll cause a buffer 
+       overflow. For a simple program like  this, though, we're letting it 
+       slide! 
+    */
+    sscanf ( inputline, "%[a-zA-Z0-9!@#$%^&*()+=/\\_-\" ]", window_title ) ; 
+
+    /* Read a comment line */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+
+    /* Read the number of affine transformations */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+    sscanf ( inputline, "%d", &num_trans ) ;
+
+    affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
+
+    /* Read a comment line */
+    checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+
+    for ( i = 0; i < num_trans; i++ )
+    {
+      /* Read an affine transformation definition */
+      checkedFGets ( inputline, sizeof ( inputline ), fptr ) ;
+      sscanf ( inputline, "%lf %lf %lf %lf %lf %lf", &affine[i].a00, &affine[i].a01,
+                       &affine[i].a10, &affine[i].a11, &affine[i].b0, &affine[i].b1 ) ;
+    }
+  }
+  else  /* No data file, set a default */
+  {
+    printf ( "ERROR opening file <%s>\n", fnme ) ;
+    strcpy ( window_title, "Koch Snowflake" ) ;
+    num_trans = 4 ;
+    affine = (AffineTrans *)malloc ( num_trans * sizeof(AffineTrans) ) ;
+    affine[0].a00 = 1/3. ;  affine[0].a01 = 0.00 ;  affine[0].a10 = 0.00 ;  affine[0].a11 = 1/3. ;
+    affine[0].b0 = 0.0 ;    affine[0].b1 = 0.0 ;
+
+    affine[1].a00 = 1/6. ;  affine[1].a01 = -1/3.*sin(FGH_PI/3.) ;   affine[1].a10 = 1/3.*sin(FGH_PI/3.) ;   affine[1].a11 = 1/6. ;
+    affine[1].b0 = 1/3. ;   affine[1].b1 = 0.0 ;
+
+    affine[2].a00 = 1/6. ;  affine[2].a01 = -1/3.*sin(-FGH_PI/3.) ;  affine[2].a10 = 1/3.*sin(-FGH_PI/3.) ;  affine[2].a11 = 1/6. ;
+    affine[2].b0 = 0.5 ;    affine[2].b1 = sqrt(3)/6. ;
+
+    affine[3].a00 = 1/3. ;  affine[3].a01 = 0.00 ;  affine[3].a10 = 0.00 ;  affine[3].a11 = 1/3. ;
+    affine[3].b0 = 2/3. ;   affine[3].b1 = 0.0 ;
+  }
+
+  for ( i = 0; i < num_trans; i++ )
+  {
+    double m00, m01, m10, m11 ;  /* Matrix "I" minus "A" */
+    double determ ;              /* Determinant of this matrix */
+
+    /* Calculate the stationary point */
+
+    m00 = 1.0 - affine[i].a00 ;
+    m01 =     - affine[i].a01 ;
+    m10 =     - affine[i].a10 ;
+    m11 = 1.0 - affine[i].a11 ;
+
+    determ = m00 * m11 - m01 * m10 ;
+
+    if ( fabs ( determ ) > 1.e-6 )
+    {
+      affine[i].statx = (  m11 * affine[i].b0 - m01 * affine[i].b1 ) / determ ;
+      affine[i].staty = ( -m10 * affine[i].b0 + m00 * affine[i].b1 ) / determ ;
+    }
+    else
+      affine[i].statx = affine[i].staty = 0.0 ;
+  }
+}
+
+int 
+main(int argc, char *argv[])
+{
+  glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE );
+
+  glutInitWindowSize(500, 250);
+  glutInitWindowPosition ( 140, 140 ) ;
+  glutInit(&argc, argv);
+
+  if ( argc > 1 )
+    readConfigFile ( argv[1] ) ;
+  else
+    readConfigFile ( "fractals.dat" ) ;
+
+  glutCreateWindow( window_title );
+
+  glClearColor(1.0, 1.0, 1.0, 1.0);
+
+  glutReshapeFunc(Reshape);
+  glutKeyboardFunc(Key);
+  glutSpecialFunc(Special);
+  glutDisplayFunc(Display);
+  glutMouseFunc(Mouse);
+  glutMotionFunc(MouseMotion);
+  glutMouseWheelFunc(MouseWheel);
+
+  glutMainLoop();
+
+  printf ( "Back from the 'freeglut' main loop\n" ) ;
+
+  free ( affine ) ;
+
+#ifdef _MSC_VER
+  /* DUMP MEMORY LEAK INFORMATION */
+  _CrtDumpMemoryLeaks () ;
+#endif
+
+  return 0;             /* ANSI C requires main to return int. */
+}